1. Field of the Invention
The present invention relates to a method for formation of copper diffusion barrier film using aluminum, and more particularly to a method for formation of copper diffusion barrier film in a method for formation of copper wiring employing a chemical-mechanical polishing (CMP) process, in which a thin aluminum film is deposited on a dielectric, the aluminum film is transformed into a nitride film basically composed of aluminum nitride (hereinafter, AlxNy), an aluminum film is deposited again on the transformed nitride film, and copper is deposited on the deposited aluminum film.
2. Description of the Prior Art
As generally known in the art, in a method for formation of metal wiring employing a CMP process, copper, which is one of wiring materials used for wiring semiconductor devices, is utilized as a metalization material which can reduce resistance-capacitance (RC) delay as its electric conductivity is low.
FIG. 1a and FIG. 1b are views showing a process for formation of copper diffusion barrier film in accordance with the prior art, wherein copper is deposited through electroplating, and then, is subjected to a conventional CMP process, which is not shown.
Copper is deposited through a Damascene process developed by IBM Inc., and is subjected to a CMP process. That is, a dielectric S1 pattern is formed on a substrate, then a copper diffusion barrier film S2 composed of titanium (Ti), titanium nitride (TiN), tantalum (Ta), and tantalum nitride (TaN), etc., is formed on the dielectric pattern, copper S3 is deposited on the copper diffusion barrier film through electroplating, and the copper is then subjected to the CMP process.
However, because of the high diffusion coefficient of copper in almost all (of the materials used in semiconductor fabrication, resulting in the deterioration of their transistor (TR) property, several kinds of diffusion barrier films have been developed and used in order to suppress the diffusion of copper.
Further, one more significant problem is that leakages between metal lines increase as pitches between the metals decrease, due to the high integration of semiconductor devices.
Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and an object of the present invention is to provide a method for formation of copper diffusion barrier film using aluminum, in which a first aluminum film is deposited on a dielectric, a surface of the first aluminum film is transformed to a nitride film basically composed of aluminum nitride (AlxNy) by plasma treating the surface of the first deposited aluminum film with NH3 or N2, then a second aluminum film is deposited again on the transformed aluminum nitride film, and copper is deposited on the second deposited aluminum film.
In order to accomplish this object, there is provided a method for formation of copper diffusion barrier film using aluminum, the method comprising: a first step of depositing a first aluminum film on a dielectric; a second step of plasma treating the surface of the first deposited aluminum with NH3 or N2, thereby transforming the plasma treated surface of the first aluminum film into a nitride film basically composed of aluminum nitride (AlxNy); a third step of depositing a second aluminum film on the transformed nitride film; and a fourth step of depositing a copper on the second aluminum film deposited.